Re: [PATCH v10 4/6] PCI: hisi: Add PCIe host support for HiSilicon SoC Hip05

[+cc Arnd, Rob]

Hi Zhou,

I have a few minor comments and two questions: one about the fact
all the config accesses are 32 bits, and another about the use of the
"msi-parent" node.

On Sat, Oct 10, 2015 at 10:59:15AM +0800, Zhou Wang wrote:

This patch adds PCIe host support for HiSilicon SoC Hip05.

Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
Signed-off-by: Gabriele Paoloni <redacted>
Signed-off-by: liudongdong <redacted>
Signed-off-by: Kefeng Wang <redacted>
Signed-off-by: qiuzhenfa <redacted>

This is a pretty long Signed-off-by chain.  If each of these people
created part of this patch, that's fine.  I'm just checking whether
that's the case, or whether some of these should be Reviewed-by,
Suggested-by, etc., per Documentation/SubmittingPatches.

"TRANSLATOR" is the more common spelling.  But if you're matching
hardware documentation, you should follow that.

+#define PCIE_SYS_CTRL20_REG                             0x20
+#define PCIE_RD_TAB_SEL                                 BIT(31)
+#define PCIE_RD_TAB_EN                                  BIT(30)
+
+#define to_hisi_pcie(x)	container_of(x, struct hisi_pcie, pp)
+
+struct hisi_pcie {
+	struct regmap *subctrl;
+	void __iomem *reg_base;
+	u32 port_id;
+	struct pcie_port pp;
+};
+
+static inline void hisi_pcie_apb_writel(struct hisi_pcie *pcie,
+					u32 val, u32 reg)
+{
+	writel(val, pcie->reg_base + reg);
+}
+
+static inline u32 hisi_pcie_apb_readl(struct hisi_pcie *pcie, u32 reg)
+{
+	return readl(pcie->reg_base + reg);
+}
+
+/*
+ * Change mode to indicate the same reg_base to base of PCIe host configure
+ * registers, base of RC configure space or base of vmid/asid context table

It's fine to use lower-case in the C code, but in English text, it
reads a little better to capitalize acronyms like VMID, ASID, APB, AR,
AW, etc.  

+ */
+static void hisi_pcie_change_apb_mode(struct hisi_pcie *pcie, u32 mode)
+{
+	u32 val;
+	u32 bit_mask;
+	u32 bit_shift;
+	u32 port_id = pcie->port_id;
+	u32 reg = PCIE_SUBCTRL_MODE_REG + 0x100 * port_id;
+
+	if ((port_id == 1) || (port_id == 2)) {
+		bit_mask = 0xc;
+		bit_shift = 0x2;
+	} else {
+		bit_mask = 0x6;
+		bit_shift = 0x1;
+	}
+
+	regmap_update_bits(pcie->subctrl, reg, bit_mask, mode << bit_shift);
+}
+
+/* Configure vmid/asid table in PCIe host */
+static void hisi_pcie_config_context(struct hisi_pcie *pcie)
+{
+	int i;
+	u32 val;
+
+	/* enable to clean vmid and asid tables though apb bus */
+	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_SYSCTRL_MODE);
+
+	val = hisi_pcie_apb_readl(pcie, PCIE_SYS_CTRL20_REG);
+	/* enable ar channel */
+	val |= PCIE_RD_TAB_SEL | PCIE_RD_TAB_EN;
+	hisi_pcie_apb_writel(pcie, val, PCIE_SYS_CTRL20_REG);
+
+	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_CONTENT_MODE);
+
+	/*
+	 * init vmid and asid tables for all PCIe devices as 0

s/as 0/to 0./

+	 * vmid table: 0 ~ 0x3ff, asid table: 0x400 ~ 0x7ff
+	 */
+	for (i = 0; i < 0x800; i++)
+		hisi_pcie_apb_writel(pcie, 0x0, i * 4);
+
+	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_SYSCTRL_MODE);
+
+	/* enable aw channel */
+	val &= (~PCIE_RD_TAB_SEL);
+	val |= PCIE_RD_TAB_EN;
+	hisi_pcie_apb_writel(pcie, val, PCIE_SYS_CTRL20_REG);
+
+	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_CONTENT_MODE);
+
+	for (i = 0; i < 0x800; i++)
+		hisi_pcie_apb_writel(pcie, 0x0, i * 4);
+
+	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_SYSCTRL_MODE);
+
+	val = hisi_pcie_apb_readl(pcie, PCIE_SYS_CTRL20_REG);
+	/* disable ar channel */
+	val |= PCIE_RD_TAB_SEL;
+	val &= (~PCIE_RD_TAB_EN);
+	hisi_pcie_apb_writel(pcie, val, PCIE_SYS_CTRL20_REG);
+	/* disable aw channel */
+	val &= ((~PCIE_RD_TAB_SEL) & (~PCIE_RD_TAB_EN));
+	hisi_pcie_apb_writel(pcie, val, PCIE_SYS_CTRL20_REG);
+
+	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_DBI_MODE);
+}
+
+static int hisi_pcie_link_up(struct pcie_port *pp)
+{
+	u32 val;
+	struct hisi_pcie *hisi_pcie = to_hisi_pcie(pp);
+
+	regmap_read(hisi_pcie->subctrl, PCIE_SUBCTRL_SYS_STATE4_REG +
+		    0x100 * hisi_pcie->port_id, &val);
+
+	return ((val & PCIE_LTSSM_STATE_MASK) == PCIE_LTSSM_LINKUP_STATE);
+}
+
+static
+int hisi_pcie_msi_host_init(struct pcie_port *pp, struct msi_controller *chip)

"static int hisi_..." as in other cases (wrap before "struct
msi_controller" instead of before "int hisi_pcie_msi_host_init").

+{
+	u64 addr;
+	struct device_node *msi_node;
+	struct resource res;
+	struct device_node *np = pp->dev->of_node;
+	struct hisi_pcie *pcie = to_hisi_pcie(pp);
+
+	msi_node = of_parse_phandle(np, "msi-parent", 0);
+	if (!msi_node) {
+		dev_err(pp->dev, "failed to find msi-parent\n");
+		return -EINVAL;
+	}
+	of_address_to_resource(msi_node, 0, &res);

Does this use the "msi-parent" node in the same way as other drivers
do?  I'm sure there must be other places where we extract struct
resource information from an "msi-parent" node, but I don't see them.

I'm trying to verify that this isn't some kind of incompatible
extension of the "msi-parent" property.  I cc'd Arnd and Rob (DT
experts).

+	addr = res.start + PCIE_GITS_TRANSLATER;
+
+	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_SYSCTRL_MODE);
+
+	hisi_pcie_apb_writel(pcie, addr & 0xffffffff, PCIE_MSI_LOW_ADDRESS);
+	hisi_pcie_apb_writel(pcie, addr >> 32, PCIE_MSI_HIGH_ADDRESS);
+	hisi_pcie_apb_writel(pcie, PCIE_MSI_ASID_ENABLE | PCIE_MSI_ASID_VALUE,
+			     PCIE_SLV_MSI_ASID);
+	hisi_pcie_apb_writel(pcie, PCIE_MSI_TRANS_ENABLE, PCIE_MSI_TRANS_REG);
+
+	hisi_pcie_change_apb_mode(pcie, PCIE_SLV_DBI_MODE);
+
+	return 0;
+}
+
+static int hisi_pcie_cfg_write(struct pcie_port *pp, int where, int  size,
+				u32 val)
+{
+	u32 reg_val;
+	u32 reg;
+	struct hisi_pcie *pcie = to_hisi_pcie(pp);
+	void *walker = &reg_val;
+
+	walker += (where & 0x3);
+	reg = where & ~0x3;
+	if (size == 4)
+		hisi_pcie_apb_writel(pcie, val, reg);
+	else if (size == 2) {
+		reg_val = hisi_pcie_apb_readl(pcie, reg);
+		*(u16 __force *) walker = val;
+		hisi_pcie_apb_writel(pcie, reg_val, reg);
+	} else if (size == 1) {
+		reg_val = hisi_pcie_apb_readl(pcie, reg);
+		*(u8 __force *) walker = val;
+		hisi_pcie_apb_writel(pcie, reg_val, reg);

This has the read/modify/write problem pointed out by Russell King:
http://lkml.kernel.org/r/E1Zenfg-0004d5-Dg@rmk-PC.arm.linux.org.uk

Is the HiSilicon hardware limited to 32-bit config accesses?  If so,
that seems like a hardware implementation defect, and this needs at
least a comment in the code.  When we figure out a good mechanism,
we'll want to taint or warn about this hardware limitation somehow.

+	} else
+		return PCIBIOS_BAD_REGISTER_NUMBER;
+
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static int hisi_pcie_cfg_read(struct pcie_port *pp, int where, int size,
+			      u32 *val)
+{
+	u32 reg;
+	u32 reg_val;
+	struct hisi_pcie *pcie = to_hisi_pcie(pp);
+	void *walker = &reg_val;
+
+	walker += (where & 0x3);
+	reg = where & ~0x3;
+	reg_val = hisi_pcie_apb_readl(pcie, reg);
+
+	if (size == 1)
+		*val = *(u8 __force *) walker;
+	else if (size == 2)
+		*val = *(u16 __force *) walker;
+	else if (size != 4)
+		return PCIBIOS_BAD_REGISTER_NUMBER;
+
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static struct pcie_host_ops hisi_pcie_host_ops = {
+	.link_up = hisi_pcie_link_up,
+	.msi_host_init = hisi_pcie_msi_host_init,
+	.wr_own_conf = hisi_pcie_cfg_write,
+	.rd_own_conf = hisi_pcie_cfg_read,

Under the rule of "do it the same way unless there's a reason to be
different," please put the hisi_pcie_cfg_read() definition before the
hisi_pcie_cfg_write() definition, and change the order of these
function pointers similarly.  That matches the order in the struct
pcie_host_ops definition and in other drivers.

+};
+
+static int __init hisi_add_pcie_port(struct pcie_port *pp,
+				     struct platform_device *pdev)
+{
+	int ret;
+	u32 port_id;
+	struct hisi_pcie *hisi_pcie = to_hisi_pcie(pp);
+
+	if (of_property_read_u32(pdev->dev.of_node, "port-id", &port_id)) {
+		dev_err(&pdev->dev, "failed to read port-id\n");
+		return -EINVAL;
+	}
+	if (port_id > 3) {
+		dev_err(&pdev->dev, "Invalid port-id: %d\n", port_id);
+		return -EINVAL;
+	}
+	hisi_pcie->port_id = port_id;
+
+	pp->ops = &hisi_pcie_host_ops;
+
+	hisi_pcie_config_context(hisi_pcie);
+
+	ret = dw_pcie_host_init(pp);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to initialize host\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __init hisi_pcie_probe(struct platform_device *pdev)
+{
+	struct hisi_pcie *hisi_pcie;
+	struct pcie_port *pp;
+	struct resource *reg;
+	int ret;
+
+	hisi_pcie = devm_kzalloc(&pdev->dev, sizeof(*hisi_pcie), GFP_KERNEL);
+	if (!hisi_pcie)
+		return -ENOMEM;
+
+	pp = &hisi_pcie->pp;
+	pp->dev = &pdev->dev;
+
+	hisi_pcie->subctrl =
+	syscon_regmap_lookup_by_compatible("hisilicon,pcie-sas-subctrl");

Indent a tab here.

+	if (IS_ERR(hisi_pcie->subctrl)) {
+		dev_err(pp->dev, "cannot get subctrl base\n");
+		return PTR_ERR(hisi_pcie->subctrl);
+	}
+
+	reg = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rc_dbi");
+	hisi_pcie->reg_base = devm_ioremap_resource(&pdev->dev, reg);
+	if (IS_ERR(hisi_pcie->reg_base)) {
+		dev_err(pp->dev, "cannot get rc_dbi base\n");
+		return PTR_ERR(hisi_pcie->reg_base);
+	}
+
+	hisi_pcie->pp.dbi_base = hisi_pcie->reg_base;
+
+	ret = hisi_add_pcie_port(pp, pdev);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, hisi_pcie);
+
+	return 0;
+}
+
+static const struct of_device_id hisi_pcie_of_match[] = {
+	{.compatible = "hisilicon,hip05-pcie",},
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, hisi_pcie_of_match);
+
+static struct platform_driver hisi_pcie_driver = {
+	.driver = {
+		   .name = "hisi-pcie",
+		   .of_match_table = hisi_pcie_of_match,
+	},
+};
+
+static int __init hisi_pcie_init(void)
+{
+	return platform_driver_probe(&hisi_pcie_driver, hisi_pcie_probe);
+}
+subsys_initcall(hisi_pcie_init);

Can you use module_platform_driver() or module_platform_driver_probe()
here instead of the subsys_initcall()?  No, I don't really know what
the difference between module_platform_driver() and
module_platform_driver_probe() is, sorry :)

Bjorn